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From:   Sven Van Asbroeck <thesven73@gmail.com>
Date:   Mon, 11 Mar 2019 14:47:59 -0400
Message-ID: <CAGngYiXyEksuMDBkrasiwwge4fgoHKKecsSHB6q0GQyEoiZXxw@mail.gmail.com>
Subject: Re: [PATCH] iio: envelope-detector: fix use-after-free on device remove
To:     Peter Rosin <peda@axentia.se>
Cc:     Tomasz Duszynski <tduszyns@gmail.com>,
        Jonathan Cameron <jic23@kernel.org>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Hi Peter,

On Mon, Mar 11, 2019 at 2:41 PM Peter Rosin <peda@axentia.se> wrote:
>
> This is false positive, AFAICT. The delayed work must have
> finished while envelope_detector_read_raw() holds the read_lock
> mutex, and it would be highly surprising if the device can go
> away while it is handling an IIO ->read_raw call. (THAT would be
> an interesting bug...)

Quite right. I had completely overlooked the fact that wait_for_completion()
cannot finish unless explicitly completed. Unlike
wait_for_completion_interruptible().

So yes, this looks like a false positive. My apologies.

Sven